nsupdate's choice of interface

[Kenneth Porter]

I've been running bind-8.2.2 for awhile now to serve a small LAN of
about 50 hosts. I'd like to use the new dhcp-3 with dns update support
to take care of keeping the DNS database populated.

I tried using nsupdate to write a record to the database, just to see
if it works, and it looks like it's using the *wrong interface* to
communicate with named. According to the nsupdate man page, it uses
resolv.conf to decide what interface to use, but the named error
message in the log file suggests otherwise.

In named.conf, I have:

zone "domain.com" IN {
       type master;
       allow-update { 127.0.0.1; };
       file "domain.com.zone";
};

In resolve.conf, I have:

search domain.com. 
nameserver 127.0.0.1

I issue the command "nslookup -d", then "update add host.domain.com. 1W
CNAME anotherhost.anotherdomain.com." and a blank line, and a bunch of
interesting stuff goes by, ending with a failure message. Inspecting
/var/log/messages, I find the message:

unapproved update from [192.168.0.32].3327 for domain.com

This is my LAN interface address. Why is nsupdate sending the update on
this interface and not through my loopback interface? Do the listen-on
or allow-transfer options affect this? They both list the LAN interface
first. Is there a way to tell nsupdate which interface to use? I see
nothing for that in the man page.

Ken
mailto:shiva at well.com
http://www.sewingwitch.com/ken/